The renewal of grant DA-00915-03 will continue the longitudinal investigation of effects of maternal narcotic addiction upon the developing infant and child. Disturbances of growth, neuromotor function, behavior and learning processes have been found in previous studies. This controlled longitudinal study is needed to document the incidence and severity of handicap in this population, as well as to determine whether disturbances are related to chronic exposure to heroin, or may be caused by poor maternal nutrition or untreated complications of pregnancy. The effect of substituting methadone treatment will be evaluated. Sixty infants born to addicts (half treated with methadone for at least two months during pregnancy) and 60 control infants whose mothers have been matched for age, ethnic group, socioeconomic and marital status, and utilization of medical resources during pregnancy, will be studied from their enrollment during pregnancy or the perinatal period through six years of age. The effects of drugs use, medical and social factors during pregnancy, characteristics and severity of newborn abstinence syndrome, and postnatal environment upon outcome measures will be analyzed. Outcome measures will include somatic growth, neuromotor function, behavioral characteristics, and intellectual, perceptual and cognitive function as tested by a variety of psychological instruments.